Dens fracture in a patient with extensive craniocervical bone pneumatization.

Craniocervical bone pneumatization in humans is very rare: only a handful of cases have been reported, predominantly in males (1). The characteristic air-filled bones are prone to fracture, even following minor trauma. Our case report (2) recently published in the December 2011 issue of Diagnostic and Interventional Radiology described abnormal extensive craniocervical bone pneumatization in a 47-year-old man; the same patient again presented to our hospital 10 months later with cervical pain after minor trauma (collapse). The patient complained of neck pain. No evidence of a neurological deficit was found. Initially performed plain radiographs of the upper cervical spine showed no evidence of a fracture. Because clinical symptoms persisted, we performed multislice computed tomography (MSCT) of the skull base and upper cervical spine using a 64-detector-row computed tomography (CT) scanner (Siemens Sensation 64, Siemens AG Sector Healthcare, Erlangen, Germany). Axial, coronal, and sagittal reconstructions were made using 0.75-mm slices. In addition to pre-existing extensive pneumatization of the skull base and atlas (Fig. a), submillimeter-scale axial images showed two thin lines at the dens at 7 and 9 o’clock (Fig. b), suspicious for thin fractures. In contrast to the previous CT findings (Fig. a), ambient soft-tissue emphysema could be observed on axial reconstructions (Fig. b, arrow). Although pre-trauma coronal reconstructions (Fig. c) showed pneumatization of the right hemicorpus of the axis, post-trauma MSCT depicted an Anderson and D’Alonzo Type III dens fracture (3) extending through the vertebral body of the axis (Fig. d, arrows). Patients who have been diagnosed with extensive craniocervical bone pneumatization need to be aware of the fragility of that anatomic region, and treating physicians should consider that even minor head or neck trauma may have serious consequences, such as fractures of the craniocervical region, in these patients. As reported earlier, the complex anatomy of the craniocervical region aggravates